shelf_bind 0.2.0

A binding handler for shelf

Binding Handler for Dart Shelf

Introduction

Provides Shelf middleware for binding Shelf request and response data to class properties.

Shelf Bind currently supports the following bindings:

• Binding to Shelf Route path variables
• Binding request Json Body

No response bindings yet.

Using

Binding to Shelf Route Path Variables

Binding a simple path variable

final routeHandler = route.router()
      ..get('/person/{name}', bind.bind(Person, {'name': #firstname}, _handlePerson))
      .handler

This binds the path variable called name as defined in the path /person/{name} to the named argument called firstname of the Person.build constructor and calling the _handlePerson function when matched.

The constructor looks like

Person.build({String firstname}) : this(firstname);

The handlers for Shelf Bind differ from the standard Shelf handlers by an extra argument which is the bound object.

_handlePerson(Person person, shelf.Request request)

Note build is the default name for the constructor. It can be overriden by passing the constructor parameter to bind

final routeHandler = route.router()
      ..get('/person/{name}', bind.bind(Person, {'name': #firstname}, _handlePerson, 
      		constructor: #foo))
      .handler

Would look for a constructor Person.foo({String firstname}).

Query Params

To bind to a query parameter

final routeHandler = route.router()
      ..get('/person{?name}', bind.bind(Person, {'name': #firstname}, _handlePerson))
      .handler

The only change was that path passed to get is now '/person{?name}'

Binding to a Json Body

Binding to a Json body is very similar. Instead you call the bindJsonBody function.

final routeHandler = route.router()
      ..post('/person', bind.bindJsonBody(Person, _handlePerson)))
      .handler

As this is binding to a Json map it does not take the binding map as above.

Example

Full source at example/binding_example.dart

The domain objects

class Person {
  final String name;

  Person(this.name);

  Person.build({String name}) : this(name);

  Person.fromJson(Map json) : this(json['name']);

  Map toJson() => { 'name': name };

  String toString() => 'Person[name: $name]';
}

A simple handler that just echos back the bound person

shelf.Response _handlePerson(Person person, shelf.Request request) {
  print(person);
  return new shelf.Response.ok('${request.method} ${request.requestedUri} '
      '=> ${person.toJson()}\n');
}

The routes and bindings

  final pathBindHandler = bind.bind(Person, {'name': #name}, _handlePerson);

  var router = (route.router()
      ..get('/person/{name}', pathBindHandler)
      ..get('/person{?name}', pathBindHandler)
      ..post('/person', bind.bindJsonBody(Person, _handlePerson)))
      .handler;

  var handler = const shelf.Stack()
      .addMiddleware(shelf.logRequests())
      .addHandler(router);

Serve it up

  io.serve(handler, 'localhost', 8080).then((server) {
    print('Serving at http://${server.address.host}:${server.port}');
  });
}

Try it out

First route

curl http://localhost:8080/person/fred

The output should look like

GET http://localhost:8080/person/fred => {name: fred}

Second route

curl http://localhost:8080/person?name=fred

Third route (json POST)

curl -d '{"name": "fred"}' http://localhost:8080/person

TODO

• Some real tests ;-)
• Link to constraints lib
• Response binding

Authors

• Anders Holmgren